#12957: In a record-update construct:ghc-stage2: panic! (the 'impossible' happened) -------------------------------------+------------------------------------- Reporter: niteria | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While compiling `Repro.hs` with `HEAD` I get this: {{{ $ ~/local/ghc-inaccessible-right-side/inplace/bin/ghc-stage2 Repro.hs [1 of 1] Compiling Repro ( Repro.hs, Repro.o ) Repro.hs:22:35: warning: [-Woverlapping-patterns] Pattern match has inaccessible right hand side In a record-update construct:ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20161209 for x86_64-unknown-linux): unused Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} It doesn't reproduce on 7.10.2. I'm 90% sure it reproduces on 8.0.2 (I have a branch with some unrelated patches). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12957 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler